| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Rod Taylor <rbt(at)zort(dot)ca> |
| Cc: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, pgsql-patches(at)postgresql(dot)org |
| Subject: | Re: Between Node |
| Date: | 2002-07-18 13:39:50 |
| Message-ID: | 4874.1026999590@sss.pgh.pa.us |
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| Lists: | pgsql-patches |
Rod Taylor <rbt(at)zort(dot)ca> writes:
> On Thu, 2002-07-18 at 00:56, Christopher Kings-Lynne wrote:
>> I believe Tom mentioned that having BETWEEN as a node would allow him to do
>> some sort of funky optimiser improvement. Is that already done or does he
>> still need to do it?
> I don't know what improvement this would be. I only touched the parser
> and executor.
In that case, this code is worse than before as far as developing plans
goes. The selectivity estimator needs to be taught about what BETWEEN
means. Currently it recognizes (x > foo AND x < bar) as a range query
--- a BETWEEN node is obviously much easier to recognize, but you still
have to add code to do it.
regards, tom lane
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